JP4046611B2 - Method for controlling the injection of fluid into an internal combustion engine - Google Patents

Abstract

Method of controlling the injection of a fluid into an internal combustion engine, comprising a piston reciprocating in a cylinder between top and bottom dead center points, and a nozzle arranged in the cylinder. The method includes injecting a fluid with an initial injection pressure into the cylinder, the fluid being ignited, so that the pressure in the cylinder increases, thereby causing the piston to be displaced towards the top dead center point, and effecting at least one injection pause during injection. The injection, immediately after the injection pause, is effected so that the injection pressure has increased in an interval of more than 0 bar and up to 2000 bar relative to an injection pressure prevailing immediately prior to the injection pause, and the injection pause is effected for a duration corresponding to an angle of rotation of an engine crankshaft in the interval 1°-30°.

Description

The present invention, for controlling a piston reciprocates between the upper and lower dead centers points in the cylinder (top and bottom dead center points) , an injection nozzle provided in the cylinder, the injection of fluid into an internal combustion engine having Performing injection of fluid into the cylinder at an initial injection pressure and igniting the fluid to increase the pressure in the cylinder, thereby moving the piston toward the bottom dead center point in the cylinder; to a method comprising the steps of performing multiple injections pause in fluid injection a.

  A combustion process in which fuel is directly injected into a cylinder and ignited by high temperature and high pressure in the cylinder is generally called a direct injection diesel process. When fuel is injected and burned in the cylinder, turbulent mixing of the combustion gas of the burning fuel occurs in the cylinder. As the fuel / gas mixture burns in the cylinder, heat is generated, which increases the gas pressure in the cylinder, thereby generating a net force on the piston. Depending on a number of parameters such as fuel injection pressure, amount of exhaust gas returning to the cylinder, timing of fuel injection, turbulent flow spreading in the cylinder, temperature in the cylinder, different combustion efficiencies and emission values can be obtained.

Conventional internal combustion engine that operates by the diesel process, soot particles and nitrogen oxides (NO _X) is relatively high emission values, such as. During the explosion stroke, a region where air is insufficient is locally generated in the cylinder, which causes incomplete combustion of the fuel injected into the cylinder. For this reason, an exhaust in the form of soot particles is generated along with the exhaust gas during the exhaust stroke.

Delay the fuel ignition so that the time for the fuel to evaporate in the cylinder and mix well with the gas is taken before the fuel ignition occurs, at the same time during the explosion or work stroke, or Prior to that, it has long been known that soot particle formation can be reduced by injecting fuel at an early point. Returning the exhaust to the combustion chamber (EGR i.e. exhaust gas recirculation), it is also known to reduce the formation of nitrogen oxides (NO _X). Thus, there are ways to reduce emissions from conventional engines. However, these known methods are limited and in extreme cases render the engine inoperable.

  When the piston moves toward the bottom dead center point during the working stroke (explosion stroke), the pressure and temperature in the cylinder drop. It has also been found that during the explosion stroke, there is relatively little turbulence or mixing of gas, fuel and soot particles formed in the cylinder, especially in the peripheral region near the cylinder wall. That is, this results in the oxidation of the soot particles formed being reduced during the explosion stroke. The soot particles not oxidized here are discharged along with the engine exhaust gas during the exhaust stroke.

It has been found that gradually increasing the injection pressure during fuel injection reduces both NO _x formation and soot formation. This is because if the fuel injection pressure is high when the injection valve is opened, a problem of increased NO _x formation occurs, and therefore a low injection pressure is desired at the start of injection. On the other hand, when the pressure is increased at the end of injection, soot is more efficiently oxidized. Therefore, it is effective to lower the injection pressure at the beginning of injection and increase the injection pressure at the end of injection.

Nitrogen oxides are formed at high combustion temperatures. To reduce the formation of the NO _X by lowering the combustion temperature, it is possible by recirculating the exhaust to the combustion chamber. However, there are cases where the exhaust cannot be sufficiently recirculated into the combustion chamber, for example, when the accelerator pedal is strongly depressed. As a result, emissions of the NO _X increases.

European as described in Patent Application Publication No. 0911511, in order to achieve low emissions of the NO _X and soot, be divided into a plurality of sections inject a single fuel injection under a constant pressure it is already known .

The problem with conventional fuel pumps is that the injection pressure during the injection process is completely dependent on the engine rpm (rpm) and the amount of fuel that will be injected during the injection process. Large amounts of injected fuel and / or high engine rpm increase the injection pressure during the injection process. Conversely, a small amount of injected fuel and / or a low engine rpm will reduce the injection pressure. This is because when the engine is operating under partial load, at low load or low rpm, the pressure increase during injection cannot be achieved, and therefore the above effect of reducing NO _x and soot formation is not realized. It means to end.

The first object of the present invention is to inject fuel into an internal combustion engine so that the above-mentioned drawbacks of the prior art are avoided and the content of NO _x and soot particles in the engine exhaust is as low as possible. Is to control.

  A second object of the present invention is to increase the oxidation of soot particles formed in the cylinder, thereby reducing the number of soot particles in the engine exhaust.

A third object of the present invention is to reduce the amount of required exhaust gas recirculation (EGR) to achieve a predetermined of the NO _X level.

  The fourth object of the present invention is to maintain a high final injection pressure of fluid injected into the engine regardless of the operating state of the engine.

The purpose is a method of the type mentioned at the outset, which comprises an initial fluid ejection pulse preceding a series of subsequent fluid ejection pulses , which gradually increase in the fluid supply rate, out of the fluid ejection pause (U _i ) The initial injection pressure (NOP _{i + 1)} for the fluid injection pulse that follows by a value within a range having a lower limit of 0 bar or more and an upper limit of 2000 bar compared to the injection pressure (NCP _i ) immediately before the first fluid injection pause. ) Increases so that the subsequent fluid injection pulse is executed, and the rotation angle (α) of the crankshaft (10) provided in the internal combustion engine (1) has a lower limit of 0 ° or more and an upper limit of 30 ° . The fluid ejection pause is performed over a period corresponding to a value within a range that is achieved .

By performing multiple injection pauses, subsequent injections move fuel, gas, and soot particles to a region where turbulence or mixing action has ceased, once again causing circulation and mixing. As a result, if the fluid injection is performed immediately after the injection stop so that the initial injection pressure increases by a value within the range from over 0 bar to 2000 bar with respect to the injection pressure shown immediately before the injection stop, the soot particles are oxidized. And oxidation is promoted. Further, the hot combustion gases in the cylinder is cooled mixed again, and at the same time soot particles are oxidized, so that the formation of the NO _X is reduced. In particular, when the injection stop is performed for a period corresponding to a value in the range of the engine / crankshaft rotation angle exceeding 0 ° to 30 °, NO _x formation is small and soot oxidation is high. Is obtained.

  In one embodiment of the present invention, an injection valve is used. The injection valve comprises an injection needle designed to cooperate with at least one injection opening provided in the injection nozzle, the injection needle being controlled by the fluid pressure generated by the high pressure generated by the high pressure pump; The fluid pressure itself is controlled by a spill valve provided on the injection valve, which injects in variable steps depending on the selected injection pause period and the next initial injection pressure selected. The valve can be opened to reduce the pressure at the valve. The injection needle can also be opened and closed by a control mechanism independent of the generated fluid pressure.

  By using such an injection valve (with the help of the injection needle control mechanism described above), an injection pause is performed, even under operating conditions that cause a small amount of injected fuel and / or low rpm, during the injection process The desired pressure increase of the fluid can be obtained. In order to enable this injection pause, the injection needle of the injection valve is controlled by closing the injection needle one or more times during the injection process. When the injection needle closes during the injection process and an injection pause occurs, the high pressure pump continues to rapidly increase the fluid pressure at the injection valve. When the injection valve is reopened after the injection stop, the fluid is injected into the cylinder at a higher injection pressure than when the injection stop has not occurred.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the accompanying drawings.

  FIG. 1 is a schematic view of an internal combustion engine (engine) 1 in which injection of fluid such as diesel fuel is performed according to the present invention. The engine 1 includes a piston 3 that reciprocates between upper and lower dead center points in the cylinder 2 and an injection nozzle 4 provided in the cylinder 2. The intake conduit 5 is guided into the cylinder 2 together with the cooperating intake valve 6, and the exhaust conduit 7 is guided out of the cylinder 2 together with the cooperating exhaust valve 8. The recess 9 at the top of the piston 3 forms a combustion chamber. In the embodiment shown in FIG. 1, the piston 3 is connected to the crankshaft 10 by a connecting rod 11, but the present invention can also be applied to an engine 1 without the connecting rod 11.

As shown in FIG. 1, when fluid is injected into the cylinder 2, the piston 3 is at top dead center. However, the piston 3 can also be located before top dead center or after top dead center when fluid begins to be injected into the cylinder 2. It is preferable to inject the entire amount of fluid directly into the recess 9 formed in the piston 3 while performing at least one injection pause U _i . That is, basically, the fluid sprays 16, 20 are directed directly to the edge 12 or slightly below it throughout the entire injection sequence. Here, the cone angle β is an angle formed between the fluid spray 16 ejected from the ejection nozzle 4 and the center line 15 of the cylinder 2. The cone angle β is also such that the fluid being injected is injected almost into the recess 9 of the piston 3 so that the fluid does not flow above the edge 12 of the recess 9 and reach the peripheral region 13 of the cylinder 2. Must be selected. 1 and 2, only two fluid sprays 16 are shown as coming from the injection nozzle 4. However, in reality, since the plurality of holes 17 are provided in the injection nozzle 4, the fluid spray 16 injected from the injection nozzle 4 has a conical or umbrella shape. At the same time that the fluid is injected into the cylinder 2, a part of the fluid is a gas introduced into the cylinder 2 consisting of air and exhaust that may be recirculated to the cylinder 2, in the compression stroke Compressed and consequently mixed with heated gas. A part of the fluid mixed with the gas ignites and burns because the temperature in the cylinder 2 is high.

  If a part of the fluid mixed with the gas in the cylinder 2 burns in a state where oxygen is insufficient, soot particles may be formed during combustion. In this specification, lambda values are defined for gas / fluid mixtures. The lambda value is also called the excess air coefficient, and is defined as a value obtained by dividing the actually supplied air amount by the theoretical air amount necessary for complete combustion. If the lambda coefficient is greater than 1, the gas / fluid mixture is lean, and if the lambda coefficient is less than 1, the gas / fluid mixture is rich. If the gas / fluid mixture is rich, incomplete combustion of the gas / fluid mixture occurs and soot particles can be formed. In order to suppress the formation of soot particles as much as possible, an effort is made to obtain a mixture of fluid and gas having a lambda coefficient of 1 or more. In an internal combustion engine such as a diesel engine in which fluid is directly injected into a cylinder and ignited by heat generated during a compression stroke, many of the engines are controlled to mix and burn, which means that the fluid being injected is stoichiometric. It is made to burn within a certain range. Where the fluid / gas mixture is close to a rich stoichiometric range, soot particles can form during combustion.

As an essential condition for increasing the turbulence and mixing of oxygen and soot particles in the cylinder 2, according to the invention, when the piston 3 is moving towards the bottom dead center of the cylinder 2, the injection pause U ₁ Is provided. When the piston 3 is in the position shown in FIG. 2, the injection pause U ₁ is performed such that no fluid is injected into the cylinder 2. The fluid 20 injected during the first injection is ignited at least partially at this stage by the heat of compression generated in the cylinder 2. As a result, the fluid burns, thereby further increasing the pressure in the cylinder 2 and, as a result, the piston 3 is pushed downward toward the bottom dead center.

Figure 2 illustrates the how the injection of fluid is how done just before the first injection pause U _1. Combustion of the fluid 20 injected prior to the injection pause U ₁ continues, but the momentum is weakening because the turbulence and mixing in the cylinder 2 are reduced. Fluid, gas, and soot particles are circulated once again in the area where turbulence or mixing action has stopped or significantly weakened by the injected fluid 16 after the injection pause, or To a greater extent, this enables and / or facilitates the oxidation of residual soot particles.

The initial injection pressure NOP ₁ is preferably set to a relatively low level so that NO _x formation is reduced. If the initial injection pressure is too high, too much mixing energy is introduced, resulting in combustion too quickly, too long combustion time, and too much fuel. Thus, since the combustion temperature becomes higher, the discharge of the NO _X increases.

It may be advantageous to increase the initial injection pressure NOP ₂ of the fluid immediately after the injection stop to a value in the range from above 0 bar to 2000 bar with respect to the injection pressure NCP ₁ shown immediately before the injection stop. I understood. Furthermore, when the injection pause U ₁ continues for a period corresponding to the rotation angle α of the engine crankshaft 10 with a value in the range of more than 0 ° to 30 °, preferably in the range of 1 ° to 20 °. It also proved advantageous.

The entire fluid injection process involving one or more injection pauses U _i is in the range from 40 ° before top dead center to 60 ° after top dead center in terms of the rotation angle α of the crankshaft 10, preferably 20 before top dead center. It shall be performed in the range from ° to 40 ° after top dead center. The fluid injection pressure, NOP and NCP (starting pressure and ending pressure, respectively) are preferably controlled to values in the range of greater than the compression pressure of the cylinder and up to 3000 bar.

When a plurality of injection pauses U _i are performed one after another in one injection process, the fluid is injected a plurality of times in a short time each time. This means that the fluid is injected into the cylinder 2 in a very short period of time. At the same time, the initial injection pressure NOP for the fluid will increase each time. Shortening the period and increasing the pressure results in a large impact and increases the degree of mixing. Piston 3, the recess 9, to form a cylinder 2, and the cylinder head 14 in a suitable manner, by providing the hole 17 so that the fluid is injected into the injection nozzle 4, is injected after the first injection pause U ₁ The region in which there is a rich fuel / gas mixture generated during and after the first injection can be controlled to be acted upon by the fluid. The initial injection pressure NOP ₁ at the time of the first fluid ejection and the start time of the first injection are also parameters that affect the existence position of the above-described region in the cylinder 2 at the time of subsequent injection (one or more times). .

Figure 3 shows the injection pressure P _inj for the rotation angle α of the engine crankshaft and a variable, fluid flow f _f, and the curve of the lift height d _n of an injection needle. According to the example, the first injection is started at the time of the crankshaft angle α ₁ before the top dead center TDC. Fluid pressure at this time is NOP _1. The first injection is performed during the period DUR ₁ . As can be seen from the curve d _n, the needle of the injection valve closes at the time of the crankshaft angle α ₂ . The fluid pressure at this point is NCP ₁ . As is apparent from the flow curve f _f , the injection pause U ₁ is provided when the needle of the injection valve is closed. During this time, no fluid flows from the injector. After the injection pause lasts for time U _1, a second injection of fluid begins at the crankshaft angle α ₃ . During the injection pause U ₁ , the fluid pressure continues to increase inside the injection valve, and when the injection needle opens at the crankshaft angle α ₃ , the fluid pressure is at the crankshaft angle α ₂ time. The pressure NOP ₂ is greater than the end-time pressure NCP ₁ . When the crankshaft angle α ₄ is reached, the injection needle of the injection valve is closed, and the injection process ends. The sequence shown in FIG. 3 can be configured to provide a plurality of injection pauses.

  The injection sequence shown in FIG. 3 can be achieved by a unit injector type injection valve, which will be described in detail later with reference to FIG.

FIG. 4 shows the flow rate f of the fluid with the rotation angle α of the engine crankshaft 10 as a variable. As can be seen from the curve in FIG. 4, the injection pause U _i is performed a plurality of times during the injection sequence. In this method, the injection sequence is intermittent. The starting pressure NOP _{i + 1} after each injection pause U _i is greater than the end pressure NCP _i shown before the injection pause U _i . As shown in FIG. 4, if the injection pressure is increased, it means that a time for injecting the increased amount of fluid for a predetermined period can be obtained every time a new injection stage is started. As mentioned at the beginning, the problem with conventional fuel pumps is that the injection pressure during the injection sequence is highly dependent on the engine rpm and the amount of fuel that is to be injected during the injection sequence. is there. When operating under small amounts of injected fuel and / or low rpm, providing multiple pauses during injection will result in the desired increase in fluid pressure during the injection sequence.

FIG. 5 shows the soot particle content with the NO _x content in the engine exhaust as a variable. The dashed curve represents the soot particle content with the NO _x content in the conventional internal combustion engine as a variable, and the solid curve represents the NO _{x in the} internal combustion engine in which fluid injection is controlled by the process according to the invention. It relates to the soot particle content with the content as a variable. As can be seen from FIG. 5, if the injection of fluid is controlled by the process according to the present invention, the soot particle content is remarkably low regardless of the value of the NO _x content of the engine exhaust.

  FIG. 6 schematically shows an injection valve 20 adapted to inject a part of the amount of compressed fuel into the combustion chamber 21 of the internal combustion engine 1. A high pressure pump 22 is connected to the injection valve 20. The high-pressure pump 22 includes a plunger 24 that reciprocates in the cylinder portion 23, and the plunger 24 compresses fluid by applying a force to the plunger 24 by a cam shaft 25. Fluid is supplied to the cylinder portion 23 from the tank 26.

  The injection valve 20 comprises an injection needle 27 adapted to cooperate with at least one injection opening 17 of the injection nozzle 4 of the injection valve 20. The injection needle 27 is provided with first and second surfaces 28 and 29 that receive pressure from the fluid. A resilient element 30 such as a needle spring pushes the injection needle 27 toward the injection opening 17. When the force from the fuel pressure acting on the second pressure receiving surface 29 is greater than the sum of the force from the fluid pressure acting on the first pressure receiving surface 28 and the force from the elastic element 30, the injection needle 27 opens, and fuel is immediately injected into the combustion chamber 21. The injection needle 27 receives an action from the relief valve 31 connected to the control unit 32. Further, the injection needle 27 cooperates with a mechanism for forcibly closing the injection needle. This mechanism is shown at 35 in FIG. The mechanism 35 is capable of opening and closing the injection needle 27 regardless of the pressure from the plunger 24 and / or the needle spring 30 even when the pressure exceeds the normal opening / closing pressure of the needle spring. The basic mode of the injection sequence in which injection is intermittently performed includes internal leakage from the high pressure side to the low pressure side of the injection valve 20, the diameter of the plunger 24, the operating speed of the plunger 24 (that is, the camshaft / rocker). It is constrained by how the arm 25 is designed) and the total effective hole area.

FIG. 7 shows what functions are obtained by the control mechanism 35. FIG. 7 shows three different injection sequences, each sequence having its own pressure sequence A, B, and C, all of the injection pressure NOP ₂ being the same, but with an injection pause (only once in FIG. 7). The injection pause between the immediately preceding injection pressure NCP ₁ and the initial injection pressure NOP ₂ immediately after the injection pause is changed according to the control method of the relief valve 31 and the injection needle 27. Note that the maximum injection pressure possible by the injection system is P _max . FIG. 7 shows what can be done when the injection needle 27 is closed until it increases to a predetermined injection pressure. In FIG. 7, the predetermined pressure levels are NOP ₁ and NOP ₂ . The injection pause can be changed freely.

In the injection sequence A (see FIG. 7), the relief valve 31 (see FIG. 6) is always closed. When NOP ₁ is reached in the cylinder portion 23, the injection needle 27 is pushed back, whereby the fluid is sprayed into the combustion chamber 21. Closing the injection needle 27 with the aid of the control mechanism 35 when forced pressure NCP _1, it waits until the injection pressure is increased to a predetermined pressure level NOP _2. When the pressure level NOP ₂ is reached, the injection needle is opened and the fluid for the next input amount is sprayed. The injection stop at this time is indicated by DUR A.

In the injection sequence B (see FIG. 7), first, the above pressure sequence is repeated for NOP ₁ , NCP ₁ and the relief valve 31 (see the injection sequence A). After reaching NCP ₁ , the relief valve 31 is opened and closed to temporarily reduce the pressure in the system. When relief valve 31 is closed, the injection needle 27 is closed, the injection pressure waits until increase to a predetermined pressure level NOP _2. When the pressure level NOP ₂ is reached, the injection needle 27 is opened to spray the next amount of fluid. The injection stop at this time is indicated by DUR B.

Injection sequence C (see Figure 7), (see injection sequence A) First, the NOP _1, NCP _1, and relief valve 31 to repeat the pressure sequence described above. After reaching NCP ₁ , the relief valve 31 is opened, the pressure is reduced to a minimum, and the relief valve 31 is immediately closed. At the same time as the relief valve 31 is closed, the injection needle 27 is closed and remains closed until the initial injection pressure NOP ₂ level is reached. When the pressure level NOP ₂ is reached, the injection needle 27 is opened to spray the next amount of fluid. The injection stop here is indicated by DUR C. If the period during which the relief valve 31 is opened during the injection stop is further extended, it is considered that the injection stop can be extended, and the start time of the pressure increase is postponed. For this reason, the timing which raise | generates injection can be controlled. In FIG. 7, the injection pressures NOP ₁ and NOP ₂ are selected as values of a certain level. It goes without saying that a different pressure increase curve can be obtained by selecting another level of injection pressure by changing the period during which the injection needle 27 is closed. Furthermore, as illustrated in FIG. 4, the fluid can be ejected with a plurality of ejection pauses.

  FIG. 8 shows another embodiment of the present invention in which two injection nozzles are provided in the cylinder 2. This enables fluid to be ejected at different angles of the first and second cone angles β1 and β2 when performing the first injection and the subsequent injection. Preferably, the first cone angle β1 when the fluid is ejected during the first ejection is selected to be the same as the cone angle β. The second cone angle β2 when injecting fluid during the subsequent injection is selected such that the fluid injected during the subsequent injection reaches the region of the rich fluid / gas mixture and mixes this region.

  Another possibility is to provide a single injection nozzle with a variable spreader structure that creates two different angles β, with the cone angle varying at each stage of injection. This is a known technique.

  The process for controlling the fuel injection of the internal combustion engine (engine) 1 according to the present invention can be applied to all operation modes of the engine 1. Preferably, the injection is controlled so that the injection pause is performed only when soot is excessively generated in the cylinder 2 during fluid combustion. When the engine 1 is operated at a high altitude, or when the engine is operated at a high ambient temperature when the air is thin, that is, when the air concentration is low, the air is expected to be taken into the cylinder. The injection pause can be executed only when the amount of oxygen molecules contained in the total amount of air is small per intake volume unit. This can also be done in a transient sequence such as opening the throttle. If the engine has a turbo driven by exhaust, the turbo reacts slowly even when the throttle is open, so that relatively little air is introduced into the cylinder 2. That is, a rich region of fluid / gas mixture is created in the cylinder 2, which increases the soot formation. Therefore, according to this process, if the injection of the next fluid is continuously executed after the stop of the injection, the soot particles are sufficiently oxidized. This will be described in more detail below.

Returning the exhaust to the cylinder 2, by means of a so-called exhaust gas recirculation i.e. EGR, but can reduce the formation of NO _X, which occurs in exchange for soot particle formation. By combining injection pause and exhaust recirculation according to this process, the soot particle content in the engine exhaust can be maintained below the legal limit. At the same time, the initial injection pressure can be kept at a low level compared to the immediately preceding injection pressure, so that the required recirculation exhaust amount is reduced. Higher the level of initial injection pressure is low, since the mixing energy to be supplied for combustion decreases, the combustion temperature is lowered, thereby also lowering the formation of NO _X. The injection pause itself has a local effect and can also reduce NO _x emissions.

Under certain operating conditions, injection with one or more injection pauses U _i according to the present invention may result in increased fuel consumption. In order to minimize such consequences, it is necessary to optimize injection pauses, use as little fluid as possible for injection, and allow the fluid to burn as quickly as possible. It has also been found that in particular, the effect of the injection pause is controlled by the structure of the cylinder and piston. If the injection pressure is further increased at the injection start time after the injection stop, the fuel required to achieve the necessary mixing is further reduced. If the injection pressure is further increased at the injection start time after the injection suspension, the combustion of the injection fluid becomes faster. However, in this case, it is necessary to consider NO _x formation as described above.

  Furthermore, the engine can be optimized according to the present invention while taking into account various load situations. For example, normal single injection may be used when the load is low, and injection may be used that pauses at least once when the load is high.

One method of increasing engine efficiency without rapidly increasing NO _x formation is to increase the amount of exhaust gas recirculated at the same time as the fluid injection timing is advanced. However, this process leads to increased soot particles in the exhaust. In order to avoid such high soot particle content, fuel consumption is negligible or not increased at all, and an injection pause is provided during fluid injection to achieve cleaner exhaust. That is. However, the large amount of recirculated exhaust complicates the engine and combustion process. Furthermore, optimizing the injection pause to achieve low fuel consumption can result in increased soot emissions. Therefore, it is considered effective to use injection suspension only at operating points where fuel consumption is not very important.

  When driving at a high altitude, there is a problem that smoke is generated due to the thin air. Since this is an operation situation that rarely occurs, in such a case, soot particle formation can be suppressed by providing one or more injection pauses. This approach is the same as that already optimized to maximize the suppression of soot particle formation.

  If the throttle is opened temporarily, particularly quickly, the problem arises that the soot particle content in the exhaust gas becomes high. Such a problem occurs because there is no time for turbocharging to increase to a high load level. A relatively long time will elapse until a sufficient level of supercharging is achieved to meet the new load conditions. On the other hand, the engine operates at a lower charge than needed. The load variation is limited by the engine control system so that the excess air is not too low, so that the turbo has time to get the desired rpm.

The injection pause U _i provides many advantages for opening the throttle. Subsequent injections after the injection pause U _i can increase the oxidation of the soot particles, which can be compensated for when the excess air is low. Also, the engine control system can quickly compensate for the load with the required higher level. The result is an engine that can react more quickly when the throttle is opened. When the injection pause U _i is provided in its basic form, as this effect decreases, more energy is imparted to the turbo, thereby obtaining the desired rpm more quickly, and by opening the throttle. The result is that the engine reacts quickly.

  The process according to the invention is applicable to two-stroke and four-stroke engines and to engines with more strokes. If the engine is a free piston engine, the angle described above may be a value relating to the distance that the piston travels in the cylinder or to a corresponding particular point in time.

  Although only diesel fuel has been described as the fluid, other flammable and non-flammable fluids such as gasoline and / or water may be used. Furthermore, it is also conceivable to introduce a fluid in a gaseous state by the injection nozzle 4.

1 is a schematic view of an internal combustion engine for injecting fluid into a cylinder according to the present invention. FIG. 2 is a schematic diagram of the internal combustion engine of FIG. 1 when injection is performed after injection stop. It is a figure which shows the injection pressure, the flow volume of a fluid, and the lift height of an injection needle by making the rotation angle of an engine crankshaft into a variable. It is a figure which shows the flow volume of the fluid which makes the rotation angle of an engine crankshaft a variable. It shows the soot particle content with the NO _x content in the engine exhaust as a variable. It is the schematic of the injection valve provided with the power control type injection needle. It is a figure which shows how an injection needle is controlled and the injection pressure at the time of injection stop and injection is changed. 1 is a schematic view of an internal combustion engine capable of performing fluid injection at various cone angles. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder 3 Piston 4 Injection nozzle 5 Intake conduit 6 Intake valve 7 Exhaust conduit 8 Exhaust valve 9 Concavity 10 Crankshaft 11 Connecting rod 12 Edge 13 Peripheral area 14 Cylinder head 15 Center line 16 Fluid spray 17 Hole (injection opening)
DESCRIPTION OF SYMBOLS 20 Fluid spray 21 Combustion chamber 22 High pressure pump 23 Cylinder part 24 Plunger 25 Cam shaft 26 Tank 27 Injection valve 28 1st surface 29 2nd surface 30 Elastic element (needle spring)
31 Relief valve 32 Control unit 35 Control mechanism

Claims (14)

A cylinder (2) piston (3) to reciprocate between top and bottom dead centers points in a cylinder injection nozzles provided in (2) (4), the injection of fluid into the internal combustion engine (1) comprising a A method of controlling,
The fluid is injected into the cylinder (2) at the initial injection pressure (NOP _i ), and the fluid is ignited to increase the pressure in the cylinder (2), thereby causing a bottom dead center point in the cylinder (2). Moving the piston (3) toward
Performing multiple injection pauses (U _i ) during fluid injection ;
In a method comprising:
Including a first fluid ejection pulse prior to a series of subsequent fluid ejection pulses, with gradually increasing fluid supply, to the ejection pressure (NCP _i ) of the fluid ejection pause (U _i ) just prior to the first fluid ejection pause. The subsequent fluid injection pulse is executed such that the initial injection pressure (NOP _{i + 1} ) for the subsequent fluid injection pulse is increased by a value within a range having a lower limit of 0 bar or more and an upper limit of 2000 bar. In addition, the fluid injection suspension is stopped over a period corresponding to a value within a range in which the rotation angle (α) of the crankshaft (10) provided in the internal combustion engine (1) has a lower limit of 0 ° or more and an upper limit of 30 °. A method characterized in that it is performed . The injection stop (U _i 2) is carried out in the range from 1 ° to 20 ° at the rotation angle (α) of the crankshaft (10). For the injection pause (U _i), the injection sequence entire fluid is performed in a range from the top dead center 40 ° to 60 ° after top dead center relates to the rotation angle of the crankshaft (10) (α) The method according to claim 1. The injection stop (U _i ), The entire fluid injection sequence is carried out in the range from 20 ° before top dead center to 40 ° after top dead center with respect to the rotation angle (α) of the crankshaft (10). The method described in 1. Injection pressure of the fluid (NOP _i, NCP _i) A method according to claim 1, characterized in that it is controlled to a value within the large range up to 3000 bar than the compression pressure of the cylinder (2). Injection valve (20) is provided with a designed injection needle to at least one injection cooperate with opening (17) provided in the injection nozzle (4) (27), those wherein the injection needle (27) is a high-pressure pump (22) is controlled by the fluid pressure generated by, under the action of the person fluid pressure itself injector (20) provided with relief valve (31), those該逃and valve (31) when the valve is opened reducing the pressure of the injection valve (20), according to claim 1, those wherein the injection needle (27) is characterized in that the generated fluid pressure can be opened and closed by independently controlling mechanism (35) Method. The method according to claim 6 , characterized in that the injection valve (20) is of unit injector type. Injection pause (U _i) A method according to claim 1, characterized in that run only when the cylinder (2) in excess amounts in the combustion of the fluid in the soot is generated. Injection pause (U _i) is, or if operating the internal combustion engine (1) at high altitudes, such as when the ambient temperature is high, the amount of oxygen molecules included in the total amount of air taken in the internal combustion engine (1) The method of claim 1, wherein the method is performed only when is relatively low per captured volume unit. 2. The method according to claim 1, wherein the injection pause (U _i ) is performed only when the internal combustion engine (1) is operated in a transient sequence. The method according to claim 1, characterized in that the fluid supplied to the cylinder (2) is a fuel such as diesel fuel. The piston (3) is provided with a recess (9) forming a combustion chamber on its upper side, and the fluid is in the shape of a cone having a cone angle (β) with respect to the center line (15) of the cylinder (2). 2. The method according to claim 1, characterized in that the fluid that is injected in and after the injection pause (U _i ) is injected directly directly into the recess (9) of the piston (3). Prior to the first injection pause (U _i ), the fluid is injected into the cylinder (2) in the form of a cone having a first cone angle (β1) with respect to the centerline (15) of the cylinder (2), Subsequent injection of fluid into the cylinder (2) takes place in the form of a cone having a second cone angle (β2) with respect to the center line (15) of the cylinder (2). The method described in 1. When a plurality of fuel injection pause is not performed, the step of recirculating exhaust gas amount smaller than the amount normally required to reduce the amount of the NO _X discharged to a predetermined level is supplied to the internal combustion engine (1) The method of claim 1, comprising:

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